I had no big problem so far with Kanotix 2006-01-RC4 (now migrated to Sidux). Maybe you want to make atleast one dist-upgrade after installing it to solve some possible problems (like kdesu not accepting your root password). Kanotix 2005-04 is not cleanly upgradable anymore, so it's not recommended to use it longer except you don't care how current your Linux installation is.